[dpm]

I doubt you'll ever stop it from regen-ing. Just as the cycle has a fixed length, I'm pretty sure there's a maximum distance between cycles too. I don't think I've ever seen more than around 500k between burns.
If I'm travelling from home to the deep South of Ireland (Cork, Limerick, Tralee) I know I'll see a regen at some stage during the day, either up or down. But whether I sit gently @ 60mph or horse it hard into a headwind, I only seem to see maybe 100km of a difference between cycles. Fuel consumption OTOH differs much more radically.

 

[Amboscott]

OK I assumed that if you went fast enough the exhaust gas would be hot enough to burn soot. Was guessing it may be 150kmh+ - bit hard to do testing in speed limit obsessed Victoria. UK & the rest of Europe are much more tolerant.

 

[pitrack_1]

clutch, 5th gear

1) Does anyone else have a grumpy 5th gear? There's a bit of graunching when I change up from 4th, like the synchro's weak and not just when cold either. No problems with other changes. Been like this for some time, reminds me of my mate's old VR Commodore wagon and even older Holdens, eg Toranas and Kingswoods!

2) Also, just recently we've developed an intermittently shuddery/grabby clutch when cold, bit like maybe there's a bit of oil getting onto it. Standard rev and slip the clutch a bit clears it, until next time. Anyone else experienced this?

Thanks,

 

[R5oss]

2) Also, just recently we've developed an intermittently shuddery/grabby clutch when cold, bit like maybe there's a bit of oil getting onto it. Standard rev and slip the clutch a bit clears it, until next time. Anyone else experienced this?

Thanks,

Yes, and I have it in writing that it's within spec. and typical for the model !!!.

 

[Tvilleguy]

OK I assumed that if you went fast enough the exhaust gas would be hot enough to burn soot. Was guessing it may be 150kmh+ - bit hard to do testing in speed limit obsessed Victoria. UK & the rest of Europe are much more tolerant.

Using Torque Pro and Pitrack's settings for the regen management, I've seen the temps increase to over double the normal running temp during a regen... I've had temps of well over 700 degrees when accelerating from 80 to 100 (and that's just letting it creep up... not gunning the throttle). Even at idle standing still the regen temps will be around the 500deg mark until it's finished the regen.

From what I've seen it doesn't seem to depend on the speed as much as it does on the load. Going up a hill for example will make the soot level decrease much quicker than sitting on a level highway. Also, slowly increasing speed (ie - 80 - 100km/hr) will drive the temps up to the high. I'd love to know what the forced regen they do at Subaru does... like if it's just revving the engine or the ecu causes it to force itself under load somehow? Does anyone know??

 

[pitrack_1]

Well, well, well, what 'ave we 'ere, then?

Well, I've just done another trip back and forwards to Sydney (ex-Canberra). A month or so ago they switched to 'alpine' (ha!) diesel... dropping the cloud point by (ahem) 4 degrees if I remember rightly. And the 'winterised' diesel drops by a whole 2 degrees. :lol:

Anyways, this is what has happened. It's a ~270km each way with approx 615m height diff:

• down= CBR -> SYD, up= SYD -> CBR.
• Temps were between 10C and 18C (OAT gauge and likely 2C high) so nothing too unusual. Little if any wind. Fine down, showery up.
• No vehicle configuration changes (e.g. tyres, tyre pressure, treatments, driving style, etc). Filled in CBR at a Woolies Petrol immediately before leaving.
• Only 1.5pax +luggage, instead of normally 2.5pax +luggage.
• Freeway running always done under cruise control, 6th gear, 110km/h (GPS speed).
• Normally, I can't break 7.0l/100km (reported) for the trip. Usually, 6.8/7.2 dn/up, with a bit of city driving thrown in to boot.
• Well this time it's 5.4l/100km down and 6.4l/100 by the time I'm back up, incl city driving. I know I've used less diesel too given the amount left in the tank.
• I've never got close to that down figure before. Or the return combined figure.
• ONE regen for the WHOLE trip. And that was in Sydney caused by the city driving. Even more so,
  • down trip started at ~40% DPF load, and did not reach 60% before Sydney (no regen).
  • up trip started at ~20% DPF load, increased to ~35% by the freeway (~10km) and decreased to ~22% by CBR (no regen).

I'm more than happy with the result given it's a 10% increase in fuel economy. But why? And will it stay?? Is it an anomaly, never to return??? Or return with 'summer' diesel???

I'll post some graphs a bit later.

 

[pitrack_1]

"Passive" Regen temp

Another thing I noticed is an Est. DPF Temp. somewhere between 350C and 400C seems to start a passive regen, judged by the soot level starting to decrease.

This generally requires sustained uphill running on a freeway at 110km/h (GPS) or more. Only other time I've got close is 'spiritedly' climbing a windy mountain pass.

 

[Tvilleguy]

That's great news mate... so do you contribute the better economy to the fuel? Won't help me up here in Townsville... nothing "Alpine" here ROFL.

 

[pitrack_1]

Changing DPF performance...changing fuel?

Well,
Just done >800kms between fills (~54l). That’s 5-10% better fuel economy (~6.7l/100km vs 7.2-7.4l/100km, measured) and one of the 2 or 3 times I’ve reached 800kms between fills.

AND there’s only 1 regen in that lot. This is totally different behaviour to previously... nothing else has changed (driver, driving style, trip routes/types/durations, tyres, pressures, temps, conditions, fuel station, etc.). The regen also happened during Sydney driving. No regens on the freeway for Canberra to/from Sydney. 5 days this week of Canberra driving (say 200-250km), has not (this time) provoked a DPF regen in when it did every 60-100km.

Certainly something’s changed that affecting the vehicle and in this case I will put it down to two things:

• Change in the fuel supplied
• Sensitivity of this vehicle to the fuel.

However you don't notice it in the driving (apart form regen frequency).

Here’s proof that the vehicle is behaving differently to before:

• Gradual soot level reduction under highway running conditions
  from the SYD->CBR 9-Jun freeway run. Note gradual reduction over ~40mins as long as the DPF temp is roughly 350C or greater.
  
  
  
• 4 vs 0 regens...same route
  Now compare the two graphs, both from the same route (Sydney to Canberra), just different days. Note in the 27-Jan graph I use the commanded throttle position to tell where the regens are occurring (this earlier trip was before I had the "DPF on" code and Torque to access it).
  
  
  
  

So I've just gone back and refilled at the same servo. Let's see what happens, I may be doing the CBR-SYD run again this weekend...

 

[pitrack_1]

Just done the CBR-SYD-CBR trip again and same result: better fuel economy, one regen for whole trip of ~600km and gradually reducing soot level on return (uphill) freeway trip.

 

[pitrack_1]

Took a week of city driving after my last trip to/from SYD/CBR to precipitate a regen. That gave me a total of approx 650kms between regens. Close to 800km between fills this time too.

One thing I did notice was regarding my theory of DPF passive regen at temp >350C. This mostly seems to hold true, however on approach to Sydney the DPF soot level was 60% with the DPF temp above 350C (it even went above 400C). However the soot level did NOT reduce this time, it increased to the 65% mark whereupon the DPF regen kicked in.

 

[ragm50]

Hey Pitrack- Still the saga goes on with Subaru. They still insist the driver must have over revved the engine. 5350rpm They have suggested the driver was going around 60km/hr when 1st gear was selected. The road speed according to the data did not change but the engine rpm did. How does the road speed not reduce when changing down a gear?????
They still could not explain why the fuel consumption increased from 6.8l/100km to 8.4l/10km after the last computer reset. The oil dilution was at around 7% when the last over rev occurred. How is the oil dilution changed and improved apart from changing the oil. Also another interesting thing they have observed in the life of this Forester was that at 8250 km approx the engine was over revved to around 5350 rpm- about 3 years ago.
Also the most recent over revving about 900 km ago was 7200rpm. Going on their calcs above 7200rpm must equate to well over 70-80 km/hr. Who would not notice this gear change and realise they should disengage the clutch. Regarding the KM reading you note when logging data - does this match the actual KMs on the speedo. Subaru seem to have a discrepancy compared to what is actual and what is logged. any ideas as to how this could vary by several 100 kms. Also going on their data the duration of the over revving was only for a few secs. Is it possible to destroy an engine in such a short time or should we be looking further for another cause. certainly the DPF light had been an issues back in FEB and March, but since the reset the DPF has been fine, but fuel has been excessive as mentioned above. Meeting with Subaru did not conclude anything, but they will check the oil for deterioration and report back. If the the oil dilution was higher than normal would you expect to see residual fuel present after waiting 3 weeks before testing??? Any thoughts on this.

 

[dpm]

A diesel engine's maximum possible RPM is governed by the maximum timing advance and fuel cetane. At some stage, you can't inject the fuel fast enough to get it to burn before TDC. Hence why power tails off above 4k rpm even on these "high-speed" diesels.

There is NO WAY, given how crappy the synchros are on the 6MT transmission that you're going to get it into 1st much above walking speed, never mind 80km/h.

Nope, the only way you'll get the engine up to those revs is by dumping oil into the intake...

 

[pitrack_1]

1st and overrevving

Hey ragm50,

Can't answer all your queries currently, but:

• I did try to engage 1st at 50km/h and it was relatively easy to do so. No baulking, no forcing, not even any graunching. So it is possible and more easily done than I would have thought. I didn't reengage the clutch however!
• I gently revved the engine whilst warm and moving with the clutch disengaged and it went up to the redline quite easily and quickly. It won't quite get to the redline under load, tapering off as it approaches. You wouldn't want to give a sudden bootful in neutral/declutched or disengage the clutch whilst still accelerating under load.
• Not sure what you mean by the km reading- if you mean km/h (speed) then yes there is a discrepancy with the speedometer reading high by roughly 8% at 100km/h compared to the parameter data which is close to GPS speed. If it's the odometer that shows some discrepancy to some logged parameter the RTA/RMS may be interested..!
• 7200rpm- who was driving the car then? It wasn't in for a service by any chance?
• if the onset of poor fuel economy coincides with an overrev event, in particular the 7200rpm one, it's possible that damage done has contributed to the poor fuel economy I suppose, and led to eventual failure. I'm guessing the engine would survive the 5350 one at least for a short time but 7200 is miles outside the spec.

As for destroying engines in a short time, have a look at the following video of how long it takes for the engine to explode after overreving under load- something's disconnected/removed on the left at approx the 22s mark. See m.youtube.com/watch?v=ZfttA0mds-c (not URLed to prevent it appearing).

 

[pitrack_1]

All quiet on the diesel front

Apart from that above, mine's been behaving since the winter kicked in. Continuous long runs between regens. I blame the winter diesel changeover. 3rd year in a row I've noticed this. I think I'll get a tank and stockpile and summer lubricity be d***ed (all right- that may be overkill)! :smile:

I'll have to find something else to keep you all (me?) amused (annoyed?) with...:biggrin:

 

[ragm50]

1) Does anyone else have a grumpy 5th gear? There's a bit of graunching when I change up from 4th, like the synchro's weak and not just when cold either. No problems with other changes. Been like this for some time, reminds me of my mate's old VR Commodore wagon and even older Holdens, eg Toranas and Kingswoods!

2) Also, just recently we've developed an intermittently shuddery/grabby clutch when cold, bit like maybe there's a bit of oil getting onto it. Standard rev and slip the clutch a bit clears it, until next time. Anyone else experienced this?

Thanks,

Patrick,
nothing to note from me on the grumpy 5th gear.
Rod

 

[ragm50]

pitrack,
With respect to KMs on odometer and ECU downloaded KMs were very different. But this could be due to 8% variation on speedo.
The 7200rpm was around 900ks back according to Subaru. current KMs 83635 plus minus a few 100 k s due to errors.
The last service was at 76695kms and the last reset was about 1500kms after that due to DPF light on 3/3/2014. The DPF came on again a 3 weeks later 25/3/2014 -this time flashing DPF. Back to Subaru for forced regen. Fuel economy bad from then on. Last oil dilution noted at 7% during the last logged freeze frame event when son was driving the car. This may have been reset at the last DPF flashing incident while at Subaru.

 

[Tvilleguy]

Hey guys,
Just thought I'd throw my latest bit of info in as I haven't chimed in for a while now. After cleaning out the EGR and reclaiming my lost boost, I have also gained a bit better fuel economy (I'm back to roughly 750km per tank combined 60/40 highway/city), my regens have gone WAY down... I was seriously having a daily if not 2 regens a day frequency... and since I first started using Torque Pro my oil dilution went from 6% to 7%... and sat there.

Now after Pitrack mentioned the 'winter fuel'... which I'm sure we don't get up here in the far north because it's not exactly cold, I decided to change fuel suppliers from BP to Shell to see if it made any difference. I'm not trying to start a brand war here, but I've been using BP Vortex 98 ULP in my previous cars (V8 commy and a worked BA sedan) for the 5 years previous to buying my current Foz... so naturally I stuck with the BP fuel, thinking it was the bees knees. Now here is the suprise...

The regens ONLY decreased when I started using the Shell fuel. Since then, and I think this is a roll on effect from the lesser amount of regens, my oil dilution has now dropped from 7% to 4%, the car is due to go in for a service next week so will be interesting to be able to log everything after fresh oil etc is put in. It's difficult to say wether or not cleaning the EGR has attributed to this... but it did definately make an improvement. One thing I have noticed is that the diesel 'rattle' is REALLY noticeable when pulled up if it's doing a regen... anyone else noticing this?

 

[pitrack_1]

One thing I have noticed is that the diesel 'rattle' is REALLY noticeable when pulled up if it's doing a regen... anyone else noticing this?

Rattle/clatter/'nailing': Yes, always. I call it rather boringly "rattle-clatter". Try revving it out whilst acceleration in a regen cycle and you can get another version.

Now after Pitrack mentioned the 'winter fuel'... which I'm sure we don't get up here in the far north because it's not exactly cold, I decided to change fuel suppliers from BP to Shell to see if it made any difference. I'm not trying to start a brand war here, but I've been using BP Vortex 98 ULP in my previous cars (V8 commy and a worked BA sedan) for the 5 years previous to buying my current Foz... so naturally I stuck with the BP fuel, thinking it was the bees knees. Now here is the suprise...
?

I should've been more specific. we get three types of diesel at differing times of the year: normal, winter and alpine. We currently get alpine diesel.

Funnily enough, I switched from Shell to Caltex.

 

[Tvilleguy]

I got those awesome christmas tree lights on the dash again (second time)... took it to Subaru who couldn't clear the code... it needs to go back in next Wed for diagnosis... they think it's the traction control or ABS module!

Here's a quick video of what it looks like...

https://www.youtube.com/watch?v=GbLsG4S5G0M